I need a polytunnel.

My plot at the moment is divided up into 4 large bed. The first bed as you go into the plot is basically clay/concrete. So today I have made the decision to put a tunnel on this bed and use the rest of the beds. The further down the plot we go the better the soil is.As I have never used a tunnel before I am asking for advice on what to buy, where to buy. How much do they cost. I will probably be looking for a 4.5 meter tunnel.Thanks in advance for any help.

I did exactly that Sunshine. Mine's 3m by 5m, wooden doors at each end. I didn't use thick enough water piping so I have had to add some extra wooden reinforcement to the frame. All in all I guess I paid around £140 on building mine, including the plastic sheeting which came in around the £70 mark via ebay. You can see on the pic below from a couple of weeks ago what I've done inside in terms of beds and planting.

I like the look of that central bed, as it gives plenty of height. As you say, thicker waterpipe is good advice

Ours are ready made ones 3m x6m and cost about £40 more, plus the wood for the edges of the bed but the cover is not as good as the one you a have built. Perhaps it will inspire miggs.. building your own means you can have the perfect size for the space!

Check ebay and local free papers for second hand ones. I have 2 both from ebay, 1 is 10m x 3m cost £90 plus around another £60 for timber frame and fixings - the cover was in good nick and its been up for over 4 years now. The other is 6m x 2.4m cost £50 but the cover wasnt too good so spent another £50 on a new one (from ebay) expect to get at least 10 years from it. It's definitely well worth keeping your eye out for these sort of bargains.